Scaffolds for cell collection or elimination

ABSTRACT

A device that includes a scaffold composition and a bioactive composition with the bioactive composition being incorporated therein or thereon, or diffusing from the scaffold composition such that the scaffold composition and/or a bioactive composition captures and eliminates undesirable cells from the body a mammalian subject. The devices mediate active recruitment, sequestration, and removal or elimination of undesirable cells from their host.

RELATED APPLICATIONS

This application is related to provisional application U.S. Ser. No. 60/936,743, filed Jun. 21, 2007, the contents which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the field of systemic disease prevention, management, and elimination.

BACKGROUND OF THE INVENTION

Some of the most prevalent and debilitating diseases in the US, and throughout the world, have several fundamental characteristics in common. First, they can be caused by subpopulations of cells which, through a variety of mechanisms, begin to impair the ability of their host to thrive. Second, the degree of severity of disease is closely linked with the ability of these undesirable cell populations to disseminate throughout multiple physiological systems. The difficulty that medicine faces in treating any condition is selectivity. The ultimate goal of treating disease is to discover a method of eliminating only the subpopulations of cells that impair function, while simultaneously sparing healthy, uninvolved, cell populations in close proximity. Many conventional drug and surgical remedies inflict damaging side effects which can either induce a new condition because they are imprecise, and thus inadvertently damage healthy cells, or further challenge the ability of an individual to thrive by making them more vulnerable to future disease.

SUMMARY OF THE INVENTION

The present invention addresses a solution to multiple obstacles associated with the in vivo elimination of distinct cell populations. First and foremost, unlike drug remedies, the device is capable of capturing, and therefore sequestering, undesirable cells either within an internal compartment or along its external surface by either filtering cells through pores in the external surface or binding cells to adhesive proteins along either its internal or external surfaces. This is a critically important innovation, because the mechanisms employed by the device to eliminate those cells which it contacts are engineered to be highly selective for only targeted cells, allowing surrounding tissue to remain unaffected. Moreover, this selectivity is particularly impressive when the device is administered systemically, in which case it is capable of first identifying, then capturing, and, if desired, eliminating cells that are in the process of spreading disease while preserving epithelial linings and other non-target tissues, as well as sparing passing blood and immune cells from interaction with treatments. Furthermore, when the target of the device is a robust cell type that requires a highly toxic agent to induce cell death, the ability of this devise to sequester cells away from their host microenvironments is particularly advantageous because concentrating these cells in a compartment without access to signaling proteins, nutrients, or adequate levels of oxygen itself induces cell death, eliminating the need to introduce a toxic substance into the host. Finally, the device overcomes obstacles such as antibiotic resistance and drug tolerance by using sequestration, which does not introduce compounds systemically, as well as a bioactive composition that includes molecules or cells capable of activating signaling pathways within the target cell population that will lead to self-destruction.

This device includes a scaffold composition which incorporates or is coated with a bioactive composition; the device attracts, adheres, captures and eliminates targeted undesirable cells. The device executes these functions by a variety of methods that include or exclude the use of a bioactive composition. Depending on the application for which the device is used, the device regulates capture and survival through the physical or chemical characteristics of the scaffold itself. For example, the scaffold composition is differentially permeable, allowing cell passage only in certain physical areas of the scaffold. The permeability of the scaffold composition is regulated, for example, by selecting or engineering a material for greater or smaller pore size, density, polymer cross-linking, stiffness, toughness, ductility, or viscoelascticity. The scaffold composition contains physical channels or paths through which cells contact a specific bioactive composition within the device or move into an intended compartment within the device. The scaffold composition is optionally organized into compartments or layers, each with a different permeability, so that cells are sorted or filtered in order to exclude targeted subpopulations from accessing or participating in the host environment while simultaneously allowing non-targeted cell types to pass through the device unaltered. Migration of target cell populations through the device is also regulated by the degradation, de- or re-hydration, oxygenation, chemical or pH alteration, or ongoing self-assembly of the scaffold composition. These processes are driven by diffusion or cell-secretion of enzymes or other reactive chemicals. Following their capture, resident cells are prohibited from accessing the host environment, which provides necessary means for survival including host cell contact, signaling molecules, sustaining nutrients, and adequate levels of oxygen. Thus, having been removed from the context of any biological niche, captured cells are sequestered or eliminated. Once the captured population is removed the scaffold composition either degrades or is collected from the subject.

Exemplary cell types that are targeted for sequestration or quarantine by this device, and are eliminated by environmental deprivation alone, and without the aid of a bioactive composition, include circulating microorganisms such as bacteria, viruses, parasites, worms, protozoa, as well as mobile mammalian tissues including immune cells, metastatic cancer cells, sickle-shaped or damaged blood cells, and epithelial cells that have lost intercellular contacts.

Optionally, a bioactive composition with means to physically bind and adhere target cells to the scaffold composition is added to ensure that cells do not escape from the scaffold once they have contacted it. Exemplary components of such an adhesive bioactive composition are either found in nature or engineered, and are listed below alongside the cell types for which they are specific.

Alternatively or in addition, the processes of cell attraction, adhesion, capture, or elimination are regulated primarily by one or more bioactive compositions. By varying the concentration of attractive molecules, the bioactive composition draws mobile or circulating cells into the device. The following are examples of attractive compounds that are used alone or in combinations to attract mobile cells to the scaffold composition: multivalent acrylamide polymers or polylysine tagged with either a sugar (galactose, fucose, ribose, or any derivatives thereof) or an amino acid (aspartate, leucine, serine) to attract bacteria; cytokines or chemokines to attract immune and metastatic cancer cells. By including particular subsets of adhesion molecules, the bioactive composition serves a selectivity function, second to the sorting and filtering function performed by the scaffold composition itself, wherein adhesion molecules that preferentially bind target cell types are incorporated into the device to differentiate between morphologically or physically similar target and non-target cell populations that might otherwise pass through porous filters. For example, the adhesion molecules including, but not limited to, the following are incorporated into bioactive compositions with means to capture microorganisms: adhesins to bind prokaryotes; polysaccharides to bind bacteria; sugar sialic acid, capsid-binding proteins, viral attachment proteins, isolated plasma membrane fractions from cellular targets to bind viruses. Alternatively adhesion molecules including, but not limited to, the following are incorporated into bioactive compositions to capture eukaryotic, or mammalian, cells: integrins, Ig superfamily members, cadherins, or selectins.

Unique combinations of attraction or adhesion molecules incorporated into the scaffold composition to differentially capture target cell populations, wherein target cell capture is either permanent or temporary depending upon which duration is most advantageous for the intended use of the device. For example, adhesive interactions with microorganisms can either be permanent or temporary depending upon the function of the device. If the device is used as a diagnostic tool for which it will be collected, semi-permanent, strong but temporary, adhesive interactions are preferred because the microorganisms can not escape from the device in the host, but can be separated from the device upon collection to allow for the isolation and identification of the captured cells by a laboratory technician. However, if the device is used as a treatment for a known infection, a permanent adhesive interaction is preferred because the microorganisms are sequestered and killed while attached to the scaffold composition and do not need to be recovered. Alternatively, the scaffold itself can be dissolved in vitro following collection to release microorganisms or mammalian cells adhered to the bioactive composition for further analysis.

By varying the components of the bioactive composition that lead to cell death, the device eliminates cells efficiently with minimal disturbance to non-targeted cell types. The device employs two primary mechanisms. By the first mechanism, target cell populations are attracted to or selectively filtered through the scaffold composition where they bind adhesive agents incorporated into the scaffold. These captured cells are then eliminated by a variety of mechanisms, all of which act exclusively within the device. By the second mechanism, the device is placed in a specific location where a target cell population resides, where it contacts neighboring cells and is anchored, e.g., adheres, in order to prevent diffusion or migration of the device. In this scenario, the closely juxtaposed cells are exposed to particles, compounds, or engineered cells that are released or allowed to diffuse from the device, disseminating only a short distance. Target cell specificity, in this second case, is achieved by the differential placement of the device, the specific compounds released, or manipulation of cell types housed within the device allowing them only to attack cells having a characteristic morphology or surface protein expression profile.

The following descriptions elucidate specific means by which target cell populations are eliminated either following capture and sequestration into the scaffold composition, or following release of particles, compounds, drug agents, or engineered cell types into the tissue surrounding an implanted device.

Antibiotic compounds including, but not limited to, amikacin, gentamicin, kanamycin, neomycin, netilmicin, streptomycin, tobramycin, teicoplanin, vancomycin, azithromycin, clarithromycin, clarithromycin, dirithromycin, erythromycin, roxithromycin, troleandomycin, amoxicillin, ampicillin, azlocillin, carbenicillin, clozacillin, dicloxacillin, flucozacillin, mezlocillin, nafcillin, penicillin, piperacillin, ticarcillin, bacitracin, colistin, polymyxin B, ciprofloxacin, enoxacin, gatifloxacin, levofloxacin, lomefloxacin, moxifloxacin, norfloxacin, oflazacin, trovafloxacin, mafenide, sulfacetamide, sulfamethizole, sulfasalazine, sulfisoxazole, trimethoprim, cotrimoxazole, demeclocycline, soxycycline, minocycline, oxytetracycline, or tetracycline are incorporated, alone or in any combination thereof, into a bioactive composition within devices used for treatment of bacterial infection.

Antiviral compounds including, but not limited to, amantadine, rimantadine, pleconaril, acyclovir, zidovudine, lamivudine, fomivirsen, zanamivir, oseltamivir, or interferon alpha are incorporated, alone or in any combination thereof, into a bioactive composition within devices used for treatment of viral infection.

Antiparasitic compounds including, but not limited to, ivermectin, diethylcarbamazine, eflornithine, melarsoprol, pentamidine, suramin, pentavalent antimonials, liposomal amphotericin B, miltefosine, chloroquine, sulphadoxine, mefloquine, artemisinins, artemether, lumefatrine, atovaquone, proguanil, chlorproguanil, dapsone, fosmidomycin, DB289, pyrimethamine, cycloguanil, sulphamethoxazole, difluoromethylornithine, antifungal trizoles (for example, posaconazole), risedronate, levamisole, or albendazole, are incorporated, alone or in any combination thereof, into a bioactive composition within devices used for treatment of parasitic, protozoan, or worm-derived infections.

Antifungal compounds including, but not limited to, sertaconazole, sulconazole, tioconazole, fluconazole, itraconazole, isavuconazole, ravuconazole, posaconizole, voriconazole, terconizole, terbinafine, amorolfine, naftifine, butenafine, anidulafungin, caspofungin, micofungin, ciclopirox, flucytosine, griseofulvin, haloprogin, tolnaftate, undecylenic acid, or ampho B lipid, are incorporated, alone or in any combination thereof, into a bioactive composition within devices used for treatment of fungal infections.

Mammalian cell types are targeted and eliminated by the device. To eliminate captured cells the device utilizes a variety of mechanisms. Bioactive compositions incorporated into the scaffold composition with means to destroy captured cells include, but are not limited to, phagocytic cells with or without compounds having means to augment their activity; engineered viruses; humanized monoclonal antibodies to activate the immune system, bind and block receptor activity, or specifically deliver a toxin with which it is bound; pro-apoptotic ligands, such as FasL, TNF, TRAIL, and caspase-activators; radioactive isotopes, such as Bismuth-213 Holmium-66, Iodine-125, Iodine-131, and Lutetium-177; toxins, including hemotoxins, necrotoxins, and neurotoxins; and chemotherapy agents.

To accomplish long-lasting weight-loss for individuals who are unable to control their fat intake or storage by any other method, and to avoid risks associated with surgical interventions, one or more device(s) are implanted on or around adipose tissue, usually located either beneath the skin (subcutaneous) or around internal organs (intraperitoneal cavity), wherein one or more bioactive compositions conjugated to the scaffold composition adhere adipocytes or pre-adipocytes (precursors that give rise to adipocytes) and induce cell death following contact with either the scaffold composition or a diffusible bioactive composition released from the device. The abundance and placement of implanted devices controls the degree to which adipocytes and pre-adipocytes are targeted, although ultimately, some tissue remains, as these cells are only undesirable when overly expanded or abundant, particularly when they reside in close proximity to and inhibit the function of vital internal organs. White adipose tissue (WAT) is targeted by the device because the alternate type, brown adipose tissue, performs functions essential for the health of the subject. Exemplary surface proteins that are used by the bioactive composition to specifically recognize immature and mature white adipocytes include, but are not limited to, serum amyloid A (SAA), adipophilin, and/or lipoprotein lipase (LPL). Adipocytes or their precursors, are eliminated by induction of apoptosis via a bioactive composition released from a stationary, and therefore implanted, device.

Neoplastic cell types, malignant or benign, are targeted and eliminated by the device. Cells that contribute to the formation of malignant neoplasms are targeted as a treatment for cancer while those cells that contribute to benign neoplasms are targeted as a preventative measure to decrease the future risk that those neoplasms, often referred to as “in situ tumors,” could acquire traits consistent with a malignant formation. One characteristic shared between all neoplasms, regardless of their potential to cause cancer, is a population of rapidly dividing cells. Therefore, to remove neoplasms from the host, the device is implanted in the area of the tumor, either in or around the cell mass, where one bioactive composition containing adhesive compounds, listed above for mammalian cells, mediates binding of tumor tissue to the scaffold, and any number of additional bioactive compositions comprising compounds or drugs with means to prevent or arrest cell division contact the captured cells in situ or diffuse from the scaffold composition into the surrounding tissue. Exemplary compounds with means to slow or retard the division of cells within a neoplasm include, but are not limited to, Dacarbazine/DTIC, Fluorouracil/5-FU, Fludarabine, Gemcitabine, Trastuzumab/Herceptin, Hydroxyurea/Hydrea, Idarubicin, Ifosfamide, Irinotecan, Cladribine/Leustatin, Mercaptopurine/Purinethol/6-MP, Methotrexate, Mithramycin/Plicamycin, Mitomycin, Mitoxanthrone/Novatrone, Navelbine/Vinorelbine, Nitrogen Mustard, Rituxan, Paclitaxel/Taxol, Docetaxel/Taxotere, Topotecan, Velban/Vinblastine, Vincristine, or Etoposide/VP-16 are incorporated, alone or in any combination thereof, into a bioactive composition within devices used for reversal of tumor formation. Cancers for which the device is used as a treatment or preventative measure at any point in the life span of the subject include, but are not limited to, acute lymphoblastic leukemia, acute myeloid leukemia, adrenocortical carcinoma, AIDS-related cancer, AIDS-related lymphoma, anal, appendix, cerebellar astrocytoma, cerebral astrocytoma, basal cell carcinoma, bile duct, bladder, one, osteosarcoma, malignant fibrous histiocytoma, brain stem glioma, brain, malignant glioma, ependymoma brain, medulloblastoma, supratentorial primitive neuroectodermal tumor, visual pathway and hypothalamic glioma, breast, bronchial adenomas, bronchial carcinoids, Burkitt's lymphoma, carcinoid tumor, gastrointestinal carcinoid tumor, carcinoma of unknown primary, central nervous system lymphoma, cervical, chronic lymphoid leukemia, chronic myelogenous leukemia, chronic myeloproliferative disorders, colon, colorectal, cutaneous T-cell lymphoma, mycosis fungoides, Sezary syndrome, endometrial, ependymoma, esophageal, Ewing's family of tumors, extracranial germ cell tumor, extragonadal germ cell tumor, extrahepatic bile duct, interocular melanoma, retinoblastoma, eye, gallbladder, gastric (stomach), gastrointestinal carcinoid tumor, gastrointestinal stromal tumor, ovarian germ cell tumor, germ cell tumor, gestational trophoblastic tumor, glioma, hairy cell leukemia, head, neck, hepatocellular, Hodgkin's lymphoma, hypopharangeal, islet cell carcinoma (endocrine pancreas), Kaposi's sarcoma, kidney (renal cell), kidney, laryngeal, lip and oral cavity, liver, lung (small cell), lung (non-small cell), Non-Hodgkin's lymphoma, Waldenstrom's macroglobulinemia, melanoma, merkel cell carcinoma, mesothelioma, metastatic squamous neck cancer with occult primary, mouth, multiple endocrine neoplasia syndrome, multiple myeloma, plasma cell neoplasm, myelodysplastic syndromes, myeloproliferative diseases, nasal cavity, paranasal sinus, nasopharyngeal, neuroblastoma, oral, oral cavity, oropharyngeal, ovarian, ovarian epithelial, ovarian low malignant potential tumor, pancreatic, parathyroid, penile, pharyngeal, pheochromocytoma, pineoblastoma, pituitary, pleuropulminary blastoma, prostate, rectal, renal pelvis and uterer, transitional cell cancer, rhabdomyosarcoma, salivary gland, soft tissue sarcoma, uterine sarcoma, skin (non-melanoma), small intestine, squamous cell carcinoma, T-cell lymphoma, testicular, throat, thymoma, thymoma carcinoma, thymic carcinoma, thyroid, unknown primary site cancer, unknown primary site carcinoma, urethral, uterine, vaginal, vulvar, or Wilm's tumor.

To prevent metastatic cells from escaping their primary tumor sites and disseminating to remote anatomical locations, one or more device(s) is implanted in or around malignant neoplasms. A bioactive composition is incorporated into or onto the scaffold composition, e.g. the scaffold not only contains cell-death-inducing agents, but also anti-metastatic compounds. Tumor cells that are preparing to enter the blood stream express cytokine receptors through which cytokines or chemokines provide migrational encouragement and instructions. Thus, bioactive compositions with means to retard or arrest metastasis include, but are not limited to, the following inhibitors of chemokine receptor activity: AMD3100, T22, TN14003, T140, TC14012, 4F-bTE, BX-471, Met-CCL5, TAK779, TAK220. By inhibiting chemokine receptor function, the preceding compounds prevent tumor cells from reacting to pro-metastatic or migratory cues present in their environment.

To capture mobile or circulating cancer cells which have broken free of their primary tumor formations, the device is administered systemically wherein it circulates in the blood, gastrointestinal tract, lymphatic fluid, or cerebral spinal fluid, and adheres and traps cancer cells by adhering to surface proteins unique to metastatic cell lines. Upon capturing these cells, the device is either used as a diagnostic tool, collected to identify the captured cells and determine the site of the primary tumor and metastasis. Alternatively, the device is used as a treatment method, and therefore, not collected, but rather a bioactive composition is incorporated within the device to eliminate the captured cell population. When the device is used to trap and kill metastatic cancer cells, and does not require collection, the scaffold composition degrades or is physically removed from the body, e.g. surgically collected. Alternatively, the device is used as an arterial stent. In this embodiment, the device is implanted and acts as a sieve, allowing all cell types to pass through, except for metastatic cancer cells that are captured by incorporating into the scaffold composition a bioactive composition with means to specifically adhere these cells. Upon contacting the stent device, captured cells are either instructed by either the flow dynamics inside of the scaffold or by a second bioactive composition to either enter an inside chamber where these cells die, or the captured cells are killed by direct interaction with a component of a second bioactive composition incorporated into the framework of the stent. Finally, a combination of these mechanisms is used to trap and kill metastatic cancer cells that either contact the framework or inner chambers of the scaffold composition. Furthermore, the bioactive compositions incorporated into either a mobile device or stent-like device can be altered to specifically adhere cells that contribute to forms of leukemia and lymphoma.

Autoimmune disease can be prevented, managed, or treated using the device. For this purpose the device is administered either locally or systemically and incorporated with a bioactive composition with means to irreversibly adhere immune cells predisposed to recognize self-antigens as “foreign,” and in response to these antigens, signal to or recruit other immune cells, proliferate, or attack host tissues. A bioactive composition is incorporated into the scaffold composition that includes self-antigens, isolated from tissue samples taken from the subject, to target autoimmune cells, as well as, adhesive proteins to bind those immune cells, and signaling proteins to either induce cell death or prevent further immune responses. Ultimately, the device captures autoimmune cells by providing an alternative target for these immune cells as a way to competitively inhibit host antigen binding.

The device targets, captures, and eliminates malfunctioning host cells that cause damage to the subject by means of failing to properly perform a given function or by accumulating within the host, interrupting the function of healthy cells. For example, the device is used to preemptively capture and remove clot-forming red blood cells as a direct result of Sickle Cell Disease. Individuals with this condition express an abnormal form of hemoglobin, called hemoglobin S (named for hemoglobin “sickle”), on the surface of red blood cells. The presence of hemoglobin S induces several morphological changes: red blood cells devolve from soft, round cells that can fit through small-diameter vessels into hardened, sickle-shaped cells, which accumulate at points along the circulatory path, ultimately decreasing the flow of blood to nearby tissues. Moreover, blood cells that express hemoglobin S have a significantly shorter life-span than cells that express the wild type form. The device is administered intravenously to a subject as either a mobile device, or an arterial stent, both of which filter blood. Sickle cells are identified and trapped either by virtue of their altered morphology or by binding to hemoglobin S, thereby adhering these cells to the scaffold composition. Following their capture, sickle cells are induced to die prematurely via pro-apoptotic ligands or they are engulfed by phagocytic cells belonging to a bioactive composition. Both methods of sickle cell elimination occur within the confines of the scaffold composition.

The device is used to aid in the treatment of peripheral and central nerve injury. When a nerve is transected, such that the axons of nerve cells comprising the nerve bundle are severed, supporting cells, called glial cells, respond by forming a “glial scar” at the site of injury. The formation of this scar prevents the axon from regenerating by creating a physically impenetrable barrier between the cell's body and its synaptic targets. To prevent the glial scar from forming, the device is placed at the site of nerve transaction and throughout the surrounding tissue wherein bioactive compositions incorporated throughout the device adhere glial cells to the scaffold composition, capturing them, and/or eliminating them, in order to prevent their migration to or proliferation at the site of injury. When used to treat injuries sustained to the central nervous system, in which nerve regeneration is also chemically prohibited, bioactive compositions incorporated into the scaffold composition further comprise compounds with means to chelate anti-regeneration ligands (such as, Nogo), block anti-regeneration receptors (the Nogo receptor, Nogo-R), and those compounds, such as growth factors, with means to promote axon elongation. Bioactive compositions with means to stimulate nerve growth and/or attenuate anti-regeneration cues are either bonded to the scaffold composition or allowed to diffuse into the surrounding tissue or space.

To eliminate organic accumulations, plaques, or waste products that impair host function, the device contains live cell types or compounds that degrade these undesirable compositions. Exemplary cell types that clear harmful debris or accumulations commonly belong to the immune system and include, but are not limited to, macrophages, neutrophils, or natural killer (NK) cells. These immune cells are engineered to specifically target cell populations when they are released from the scaffold composition, however, these cells also reside inside the device and clear debris from the scaffold composition as captured cell types are eliminated. The presence of these cells allows the device to continually trap cells. To activate resident phagocytic cells, adiponectin, a protein normally produced by adipocytes and known to facilitate phagocytosis by forming a bridge between dead cells and macrophages, is further incorporated into one or more of the bioactive composition(s).

Genetically-manipulated viruses that are engineered to specifically attack target cell populations are incorporated into one or more bioactive composition(s) of the devise. These engineered viruses either permanently reside within the confines of the scaffold composition or, alternatively, diffuse into surrounding tissues following implantation of the device, dependent upon the precision of their specificity and the physical characteristics of the device placement. For example, oncolytic viruses are engineered to specifically infect cancer cells either by modification of their coat protein specificity or by altering the genome of the virus to render it replication-incompetent in any cell type other than a cancer cell. Adenovirus and herpes simplex virus are often used to infect cancer cells and are included in the bioactive composition of the device. Alternatively, some oncolytic viral strains are specific for cancer cells either due to the increased susceptibility of most cancer cells, as in the case of rhabdovirus, or, as a result of their natural specificity, as in the case of poliovirus, which evolved to be a neuropathogen. Furthermore, these viruses kill tumor cells either by lysing the cell, which is a normal function of a virus, or by delivering pro-apoptotic and/or anti-angiogenic genes to induce cell death, which is a genetically engineered function of these viruses. To prevent the host immune system from recognizing engineered viruses and inducing a response that could eliminate them before they have executed their function, e.g. infect cancer cells, these viruses are coated with a polymer, such as polyethylene glycol, which serves as a shield to antibodies.

The device controls and directs the migration of cells through its structure. Chemical affinities are used to channel cells towards a specific area of contact or quarantine. For example, attraction and adhesion molecules are used to attract or retard the migration of cells, respectively. By varying the density and mixture of those bioactive substances, the device controls the specificity of capture and location of adhesion. The density and mixture of these bioactive substances is controlled by initial doping levels or concentration gradient of the substance, by embedding the bioactive substances in scaffold material with a known leaching rate, by release as the scaffold material degrades, by diffusion from an area of concentration, by interaction of precursor chemicals diffusing into an area, or by production/excretion of compositions by resident support cells. The physical or chemical structure of the scaffold also regulates the diffusion of bioactive agents through the device.

The device is composed of a biocompatible material. One of the most common embodiments of the device incorporates the extracellular matrix (ECM) as a component of one or more bioactive composition(s) in order to adhere a wide variety of foreign and host cell types. In this case, the ECM is chemically cross-linked to the scaffold composition. Regardless of the tissue of origin, ECM components generally include three general classes of macromolecules: collagens, proteoglycans/glycosaminoglycans (PG/GAG), and glycoproteins, e.g., fibronectin (FN), laminin, and thrombospondin. ECM components associate with molecules on the cell surface and mediate adhesion and/or motility. Preferably, the ECM component associated with the scaffold is a proteoglycan attachment peptide or cyclic peptide containing the amino acid sequence arginine-glycine-aspartic acid (RGD). Proteoglycan attachment peptides are selected from the group consisting of G₄RGDSP (SEQ ID NO: 1), XBBXBX (SEQ ID NO: 2), PRRARV (SEQ ID NO: 3), YEKPGSPPREVVPRPRPGV (SEQ ID NO: 4), RPSLAKKQRFRHRNRKGYRSQRGHSRGR (SEQ ID NO: 5), and RIQNLLKITNLRIKFVK (SEQ ID NO: 6), and cell attachment peptides are selected from the group consisting of RGD, RGDS, LDV, REDV, RGDV, LRGDN (SEQ ID NO: 7), IKVAV (SEQ ID NO: 8), YIGSR (SEQ ID NO: 9), PDSGR (SEQ ID NO: 10), RNIAEIIKDA (SEQ ID NO: 11), RGDT, DGEA, and VTXG.

Components of the ECM, e.g., FN, laminin, and collagen, interact with the cell surface via the integrin family of receptors, a group of divalent cation-dependent cell surface glycoproteins that mediate cellular recognition and adhesion to components of the ECM and to other cells. Ligands recognized by integrins typically contain an RGD amino acid sequence that is expressed in many ECM proteins. Exemplary molecules that mediate cell adhesion and/or movement include FN, laminin, collagen, thrombospondin 1, vitronectin, elastin, tenascin, aggrecan, agrin, bone sialoprotein, cartilage matrix protein, fibronogen, fibrin, fibulin, mucins, entactin, osteopontin, plasminogen, restrictin, serglycin, SPARC/osteonectin, versican, von Willebrand Factor, polysaccharide heparin sulfate, cell adhesion molecules including connexins, selectins, collagen, RGD (Arg-Gly-Asp) and YIGSR (Tyr-Ile-Gly-Ser-Arg) (SEQ ID NO: 9) peptides, glycosaminoglycans (GAGs), hyaluronic acid (HA), integrins, selectins, cadherins and members of the immunoglobulin superfamily. Carbohydrate ligands of the ECM include the polysaccharides hyaluronic acid, and chondroitin-6-sulfate.

To create a multifunctional device, a plurality of bioactive compositions are covalently linked to the scaffold composition, keeping these compositions relatively immobilized in or on the scaffold composition. In other cases, additional bioactive compositions are noncovalently associated with the scaffold. Noncovalent bonds are generally one to three orders of magnitude weaker than covalent bonds permitting diffusion of the factor within the compartments of the device, and ultimately, out of the scaffold and into surrounding tissues. Noncovalent bonds include electrostatic, hydrogen, van der Waals, π aromatic, and hydrophobic interactions.

The scaffold composition is also contacted with a second bioactive composition. The second bioactive composition is sometimes non-covalently associated with the scaffold composition to yield a layered scaffold, i.e., a scaffold composition that includes one or more bioactive substances. The application of contacting of the scaffold composition with a second bioactive composition is optionally repeated to yield a plurality of scaffold structures, e.g., each of the contacting steps is characterized by a different amount of the second bioactive composition to yield a gradient of the second bioactive composition in the scaffold device. Rather than altering the amount of composition, subsequent contacting steps involve a different bioactive composition, i.e., a third, fourth, fifth, sixth . . . , composition or mixture of compositions, that is distinguished from the prior compositions or mixtures of prior doping steps by the structure or chemical formula of the factor(s). The layers, or components of the scaffold form a gradient to lure undesirable cells into the device to one another and/or insertion of semi-permeable, permeable, or impermeable membranes within or at one or more boundaries of the device to further controls/regulate the locomotion of cells or bioactive compositions into the scaffold to trap the cells therein, as well as the elimination of resident cell populations.

The scaffold composition can be constructed using a variety of materials that will be chosen according to its desired function. In all cases, the scaffold composition is biocompatible, meaning that the scaffold composition itself does not induce damage or activate the host immune system. The composition is bio-degradable/erodable or resistant to breakdown in the body. Relatively permanent (degradation resistant) scaffold compositions include metals and some polymers such as silk.

The scaffold composition is used for a variety of functions for which one or more of the bioactive compositions destroy(s) the captured cell population. Therefore, the scaffold itself does not need to exist indefinitely either internal or external to the host, and is composed of a biodegradable material. Breakdown of the scaffold composition as a result of any or all of the following events: the captured cells release one or more corrosive compound(s), the local host environment where the scaffold resides contains one or more corrosive compound(s), the process of eliminating the captured cells produces one or more corrosive compound(s), the bioactive composition itself compromises the structural integrity of the scaffold, the scaffold disassembles upon collection. In one example, cells mediate degradation of the scaffold matrix, i.e., the scaffold composition is enzymatically digested by a composition elicited by a resident cell. In this case, polymer main chains or cross-links contain compositions, e.g., oligopeptides, that are substrates for collagenase or plasmin, or other enzymes produced by within or adjacent to the scaffold.

For some applications, the scaffold composition preferably degrades at a predetermined rate based on a physical parameter selected from the group consisting of temperature, pH, hydration status, and porosity, the cross-link density, type, and chemistry or the susceptibility of main chain linkages to degradation or it degrades at a predetermined rate based on a ratio of chemical polymers. For example, a high molecular weight polymer comprised of solely lactide degrades over a period of years, e.g., 1-2 years, while a low molecular weight polymer comprised of a 50:50 mixture of lactide and glycolide degrades in a matter of weeks, e.g., 1, 2, 3, 4, 6, 10 weeks. A calcium cross-linked gels composed of high molecular weight, high guluronic acid alginate degrade over several months (1, 2, 4, 6, 8, 10, 12 months) to years (1, 2, 5 years) in vivo, while a gel comprised of low molecular weight alginate, and/or alginate that has been partially oxidized, will degrade in a matter of weeks.

Exemplary scaffold compositions include polylactic acid, polyglycolic acid, PLGA polymers, alginates and alginate derivatives, gelatin, collagen, fibrin, hyaluronic acid, laminin rich gels, agarose, natural and synthetic polysaccharides, polyamino acids, polypeptides, polyesters, polyanhydrides, polyphosphazines, poly(vinyl alcohols), poly(alkylene oxides), poly(allylamines)(PAM), poly(acrylates), modified styrene polymers, pluronic polyols, polyoxamers, poly(uronic acids), poly(vinylpyrrolidone) and copolymers or graft copolymers of any of the above. One preferred scaffold composition includes an RGD-modified alginate.

For some applications, porosity of the scaffold composition influences selectivity of the cells captured by or permitted through the device. Pores are nanoporous, microporous, or macroporous. For example, the diameter of nanopores are less than about 10 nm; micropore are in the range of about 100 nm-20 μm in diameter; and, macropores are greater than about 20 μm (preferably greater than about 100 μm and even more preferably greater than about 400 μm). In one example, the scaffold is macroporous with aligned pores of about 400-500 μm in diameter.

The devices are manufactured in their entirety in vitro. Furthermore the devices can be assembled around or in contact with engineered cultured cells or viruses with means to attract, adhere, or eliminate captured target cells, in order to produce a scaffold and bioactive composition combination that includes living or dead cells. Alternatively, the device is manufactured in two or more (3, 4, 5, 6, . . . 10 or more) stages in which one layer or compartment is made and coated with bioactive composition followed by the construction of a second, third, fourth or more layers, which are in turn coated with bioactive material in sequence. Each layer or compartment is identical to the others or distinguished from one another by the number, genotype, or phenotype of the seed cell population as well as distinct chemical, physical and biological properties of the scaffold or bioactive composition.

Therapeutic applications of the device include diagnosis of infection by microorganisms, or the discovery and diagnosis of diseased host tissues that contribute to sickle cell disease, leukemia, metastatic cancer, autoimmune conditions, or inflammatory disease. Moreover, this device is used as a diagnostic tool to capture and identify cancer cells that have metastasized potentially from multiple primary tumors, thereby eliminating the need for multiple biopsies or more invasive surgical options. Alternatively, this devise is used as a medical treatment to eliminate microorganisms, malignant neoplasms, leukemia, lymphoma, arterial blockages, adipose tissue, inflammation, glial scars, and protein deposits. Furthermore, this devise can be used for preventative medicine to assess exposure to microorganisms, eliminate benign neoplasms, eliminate immune cells that activate to self-antigens, as well as prevent arterial build-up or glial scaring following nerve damage.

Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims. References cited are hereby incorporated by reference.

DETAILED DESCRIPTION OF THE INVENTION

The device contains a scaffold composition incorporated with one or more bioactive compositions. The most fundamental functions of the device are capturing and eliminating target cells from a host organism. In this case, the “host” is any mammalian subject and the term “host cell” describes any cell that is recognized by a healthy immune system as displaying self-antigens. Alternatively, a “foreign cell” is meant to describe any cell that is recognized by a healthy immune system as displaying non-self, or foreign, surface antigens as well as any cell that was not born, or generated, within the host organism. The term “undesirable” cell is meant to describe any cell that increases the risk or susceptibility of the host to infection or disease, or any cell that decreases the ability of the host to thrive. The term “scaffold composition” is meant to describe a biocompatible, biodegradable or non-biodegradable frame, used to deliver a bioactive composition to a particular location of the body, or to create a physical niche into or onto which targeted cell types accumulate and, by this act, are destroyed or removed from the context of the host body. The term, “bioactive composition” is meant to describe any combination of molecules, compounds, proteins, or cell types having means to alter the behavior of the target cell type. The bioactive compositions used within the invented device either remain incorporated with the scaffold composition, or they may diffuse from the scaffold structure to contact surrounding target tissues.

Resident cells, incorporated into a bioactive composition prior to administering the device to a subject, including immune cells and viruses, are optionally genetically manipulated by the introduction of exogenous genetic sequences or the inactivation or modification of endogenous sequences. For example, recombinant genes are introduced to cause the cells to encode or make proteins that are otherwise lacking in the host or target tissue. Production of scarce but desirable proteins (in the context of certain tissues) is augmented by transplanting genetically engineered cells. General mammalian cell culture techniques, cell lines, and cell culture systems are described in Doyle, A., Griffiths, J. B., Newell, D. G., (eds.) Cell and Tissue Culture: Laboratory Procedures, Wiley, 1998, the contents of which are incorporated herein by reference.

Scaffold Compositions and Architecture

Components of the scaffolds are organized in a variety of geometric shapes (e.g., beads, pellets), niches, planar layers (e.g., thin sheets). For example, multi-component scaffolds are constructed in concentric layers each of which is characterized by different physical qualities (% polymer, % cross-linking of polymer, chemical composition of scaffold, pore size, porosity, and pore architecture, stiffness, toughness, ductility, viscoelasticity, and or composition of bioactive substances such as growth factors, homing/migration factors, differentiation factors. Each niche has a specific effect on a cell population, e.g., promoting or inhibiting a specific cellular function, attraction, adhesion, elaboration of secreted factors or enzymes, or induction of cell death. Cells implanted within the scaffold prior to administration of the device to a subject are engineered to target specific cell populations only, and permitted to migrate out of the scaffold to eliminate a target tissue. For example, engineered viruses and activated macrophages are released from the scaffold composition to either infect target cells or clear debris from the surrounding tissue. For some purposes, the device acts locally, and is therefore placed or transplanted into, on, or proximal to a target tissue, wherein that target tissue resides either internal or external (skin surfaces) to the body. Alternatively, the device acts systemically and is therefore introduced into the gastrointestinal tract, blood supply, lymphatic fluid, or cerebral spinal fluid. Devices are introduced into or onto a bodily tissue using a variety of known methods and tools, e.g., gelatin-coated pill, spoon, tweezers or graspers, hypodermic needle, endoscopic manipulator, endo- or trans-vascular-catheter, stereotaxic needle, snake device, organ-surface-crawling robot (United States Patent Application 20050154376; Ota et al., 2006, Innovations 1:227-231), minimally invasive surgical devices, surgical implantation tools, and transdermal patches. Devices can also be assembled in place, for example by sequentially injecting or inserting matrix materials. Scaffold devices are optionally recharged with cells or with bioactive compounds.

A scaffold or scaffold device is the physical structure upon which or into which cells associate or attach, and a scaffold composition is the material from which the structure is made. For example, scaffold compositions include biodegradable or permanent materials such as those listed below. The mechanical characteristics of the scaffold vary according to the application or tissue type for which elimination is sought. In the series of experiments described in the examples, a polymer formulation consisting of poly(lactide-co-glycolide) (PLG) was used. Other preferred polymers include but are not limited to poly(lactide)s, poly(glycolide)s, poly(lactic acid)s, poly(glycolic acid)s, polyanhydrides, polyorthoesters, polyetheresters, polycaprolactones, polyesteramides, polycarbonates, polycyanoacrylates, polyurethanes, polyacrylates, and blends or copolymers of the above. A scaffold or scaffold device is biodegradable (e.g., collagen, alginates, polysaccharides, polyethylene glycol (PEG), poly(glycolide) (PGA), poly(L-lactide) (PLA), or poly(lactide-co-glycolide) (PLGA) or permanent (e.g., silk). In one embodiment, the scaffold or scaffold device comprises a biocompatible polymer matrix that may optionally be biodegradable in whole or in part. A hydrogel is one example of a suitable polymer matrix material. Examples of materials which can form hydrogels include polylactic acid, polyglycolic acid, PLGA polymers, alginates and alginate derivatives, gelatin, collagen, agarose, natural and synthetic polysaccharides, polyamino acids such as polypeptides particularly poly(lysine), polyesters such as polyhydroxybutyrate and poly-.epsilon.-caprolactone, polyanhydrides; polyphosphazines, poly(vinyl alcohols), poly(alkylene oxides) particularly poly(ethylene oxides), poly(allylamines)(PAM), poly(acrylates), modified styrene polymers such as poly(4-aminomethylstyrene), pluronic polyols, polyoxamers, poly(uronic acids), poly(vinylpyrrolidone) and copolymers of the above, including graft copolymers. In another embodiment, the scaffolds may be fabricated from a variety of synthetic polymers and naturally-occurring polymers such as, but not limited to, collagen, fibrin, hyaluronic acid, agarose, and laminin-rich gels. In the case of biodegradable structures, the composition is degraded by physical or chemical action, e.g., level of hydration, heat or ion exchange or by cellular action, e.g., elaboration of enzyme, peptides, or other compounds by nearby or resident cells. The consistency varies from a soft/pliable (e.g., a gel) to glassy, rubbery, brittle, tough, elastic, stiff. The structures contain pores, which are nanoporous, microporous, or macroporous, and the pattern of the pores is optionally homogeneous, heterogeneous, aligned, repeating, or random.

Alginates are versatile polysaccharide based polymers that may be formulated for specific applications by controlling the molecular weight, rate of degradation and method of scaffold formation. Coupling reactions can be used to covalently attach bioactive epitopes, such as the cell adhesion sequence RGD to the polymer backbone. Alginate polymers are formed into a variety of scaffold types. Injectable hydrogels can be formed from low MW alginate solutions upon addition of a cross-linking agents, such as calcium ions, while macroporous scaffolds are formed by lyophilization of high MW alginate discs. Differences in scaffold formulation control the kinetics of scaffold degradation. Release rates of morphogens or other bioactive substances from alginate scaffolds is controlled by scaffold formulation to present morphogens in a spatially and temporally controlled manner. This controlled release not only eliminates systemic side effects and the need for multiple injections, but can be used to create a microenvironment that activates host cells at the implant site and transplanted cells seeded onto a scaffold.

The scaffold comprises a biocompatible polymer matrix that is optionally biodegradable in whole or in part. A hydrogel is one example of a suitable polymer matrix material. Examples of materials which can form hydrogels include polylactic acid, polyglycolic acid, PLGA polymers, alginates and alginate derivatives, gelatin, collagen, agarose, natural and synthetic polysaccharides, polyamino acids such as polypeptides particularly poly(lysine), polyesters such as polyhydroxybutyrate and poly-epsilon, poly-caprolactone, polyanhydrides; polyphosphazines, poly(vinyl alcohols), poly(alkylene oxides) particularly poly(ethylene oxides), poly(allylamines)(PAM), poly(acrylates), modified styrene polymers such as poly(4-aminomethylstyrene), pluronic polyols, polyoxamers, poly(uronic acids), poly(vinylpyrrolidone) and copolymers of the above, including graft copolymers.

Scaffold Fabrication

Scaffolds are fabricated from a variety of synthetic polymers and naturally-occurring polymers such as, but not limited to, collagen, fibrin, hyaluronic acid, agarose, and laminin-rich gels. One preferred material for the hydrogel is alginate or modified alginate material. Alginate molecules are comprised of (1-4)-linked β-D-mannuronic acid (M units) and a L-guluronic acid (G units) monomers, which can vary in proportion and sequential distribution along the polymer chain. Alginate polysaccharides are polyelectrolyte systems which have a strong affinity for divalent cations (e.g. Ca⁺², Mg⁺², Ba⁺²) and form stable hydrogels when exposed to these molecules. See Martinsen A., et al., Biotech. & Bioeng., 33 (1989) 79-89.) For example, calcium cross-linked alginate hydrogels are useful as a matrix for other cell types. cross-linked alginate hydrogels have been used in many biomedical applications, including materials for dental impressions (Hanks C. T., et al., Restorative Dental Materials; Craig, R. G., ed., Ninth Edition, Mosby (1993)), wound dressings (Matthew I. R. et al., Biomaterials, 16 (1995) 265-274), an injectable delivery medium for chondrocyte transplantation (Atala A., et al., J Urology, 152 (1994) 641-643), and an immobilization matrix for living cells (Smidsrod O., et al, TIBTECH 8 (1990) 71-78).

An exemplary device utilizes an alginate or other polysaccharide of a relatively low molecular weight, preferably of size which, after dissolution, is at the renal threshold for clearance by humans, e.g., the alginate or polysaccharide is reduced to a molecular weight of 1000 to 80,000 daltons. Preferably, the molecular mass is 1000 to 60,000 daltons, particularly preferably 1000 to 50,000 daltons. It is also useful to use an alginate material of high guluronate content since the guluronate units, as opposed to the mannuronate units, provide sites for ionic cross-linking through divalent cations to gel the polymer. U.S. Pat. No. 6,642,363, incorporated herein by reference discloses methods for making and using polymers containing polysaccharides such as alginates or modified alginates.

Useful polysaccharides other than alginates include agarose and microbial polysaccharides such as those listed in the table below.

Polysaccharide Scaffold Compositions Polymers^(a) Structure Fungal Pullulan (N) 1,4-; 1,6-α-D-Glucan Scleroglucan (N) 1,3; 1,6-α-D-Glucan Chitin (N) 1,4-β-D-Acetyl Glucosamine Chitosan (C) 1,4-β•-D-N-Glucosamine Elsinan (N) 1,4-; 1,3-α-D-Glucan Bacterial Xanthan gum (A) 1,4-β•-D-Glucan with D-mannose; D-glucuronic Acid as side groups Curdlan (N) 1,3-β•-D-Glucan (with branching) Dextran (N) 1,6-α-D-Glucan with some 1,2; 1,3-; 1,4-α-linkages Gellan (A) 1,4-β•-D-Glucan with rhamose, D-glucuronic acid Levan (N) 2,6-β-D-Fructan with some β-2,1-branching Emulsan (A) Lipoheteropolysaccharide Cellulose (N) 1,4-β-D-Glucan ^(a)N-neutral, A = anionic and C = cationic.

The scaffolds of the invention are porous or non-porous. For example, the scaffolds are nanoporous having a diameter of less than about 10 nm; microporous wherein the diameter of the pores are preferably in the range of about 100 nm-20 μm; or macroporous wherein the diameter of the pores are greater than about 20 μm, more preferably greater than about 100 μm and even more preferably greater than about 400 μm. In one example, the scaffold is macroporous with aligned pores of about 400-500 μm in diameter. The preparation of polymer matrices having the desired pore sizes and pore alignments are described in the Examples. Other methods of preparing porous hydrogel products are known in the art. (U.S. Pat. No. 6,511,650 incorporated herein by reference).

Bioactive Compositions

The device includes one or more bioactive compositions. Bioactive compositions are purified naturally-occurring, synthetically produced, or recombinant compounds, e.g., polypeptides, nucleic acids, small molecules, or other agents. The compositions described herein are purified. Purified compounds are at least 60% by weight (dry weight) the compound of interest. Preferably, the preparation is at least 75%, more preferably at least 90%, and most preferably at least 99%, by weight the compound of interest. Purity is measured by any appropriate standard method, for example, by column chromatography, polyacrylamide gel electrophoresis, or HPLC analysis.

The bioactive composition affects cell mobility and survival by inducing changes in the surface protein expression or interaction, or intracellular signaling of a cell, by restricting its access to environmental cues, or by contacting a cell with a modified cell type with means to induce cell death, compromise the structural integrity of the target cell, or engulf the target cell. For example, at least one cell adhesion molecule is incorporated into or onto the polymer matrix. Such molecules are incorporated into the polymer matrix prior to polymerization of the matrix or after polymerization of the matrix. Examples of cell adhesion molecules include but are not limited to peptides, proteins and polysaccharides. More specifically, cell adhesion molecules include fibronectin, laminin, collagen, thrombospondin 1, vitronectin, elastin, tenascin, aggrecan, agrin, bone sialoprotein, cartilage matrix protein, fibronogen, fibrin, fibulin, mucins, entactin, osteopontin, plasminogen, restrictin, serglycin, SPARC/osteonectin, versican, von Willebrand Factor, polysaccharide heparin sulfate, connexins, collagen, RGD (Arg-Gly-Asp) and YIGSR (Tyr-Ile-Gly-Ser-Arg) (SEQ ID NO: 9) peptides and cyclic peptides, glycosaminoglycans (GAGs), hyaluronic acid (HA), condroitin-6-sulfate, integrin ligands, selectins, cadherins and members of the immunoglobulin superfamily. Other examples include neural cell adhesion molecules (NCAMs), intercellular adhesion molecules (ICAMs), vascular cell adhesion molecule (VCAM-1), platelet-endothelial cell adhesion molecule (PECAM-1), L1, and CHL1.

Particularly preferred cell adhesion molecules of the invention are peptides or cyclic peptides containing the amino acid sequence arginine-glycine-aspartic acid (RGD) which is known as a cell attachment ligand and found in various natural extracellular matrix molecules. A polymer matrix with such a modification provides cell adhesion properties to the scaffold of the invention, and sustains long-term survival of mammalian cell systems, as well as supporting cell growth and differentiation.

Examples of some of these molecules and their function are shown in the following table.

ECM Proteins and peptides and role in cell function Seq. Protein Sequence ID No: Role Fibronectin RGDS Adhesion LDV Adhesion REDV Adhesion Vitronectin RGDV Adhesion Laminin A LRGDN 7 Adhesion IKVAV 8 Neurite extension Laminin B1 YIGSR 9 Adhesion of many cells, via 67 kD laminin receptor PDSGR 10 Adhesion Laminin B2 RNIAEIIKDA 11 Neurite extension Collagen 1 RGDT Adhesion of most cells DGEA Adhesion of platelets, other cells Thrombospondin RGD Adhesion of most cells VTXG Adhesion of platelets

-   Hubbell, J A (1995): Biomaterials in tissue engineering. -   Bio/Technology 13:565-576. One-letter abbreviations of amino acids     are used, X stands for any amino acid.

Additional examples of suitable cell adhesion molecules are shown below.

Amino acid sequences specific for proteoglycan binding from extracellular matrix proteins SEQ. ID. SEQUENCE NO. PROTEIN XBBXBX* 12 Consensus PRRARV 13 Fibronectin YEKPGSPPREVVPRPRPGV 14 Fibronectin RPSLAKKQRFRHRNRKGYRSQRGHSRGR 15 Vitronectin rIQNLLKITNLRIKFVK 16 Laminin

Coupling of the cell adhesion molecules to the polymer matrix is accomplished using synthetic methods which are in general known to one of ordinary skill in the art and are described in the examples. Approaches to coupling of peptides to polymers are discussed in Hirano and Mooney, Advanced Materials, p. 17-25 (2004). Other useful bonding chemistries include those discussed in Hermanson, Bioconjugate Techniques, p. 152-185 (1996), particularly by use of carbodiimide couplers, DCC and DIC (Woodward's Reagent K). Since many of the cell adhesion molecules are peptides, they contain a terminal amine group for such bonding. The amide bond formation is preferably catalyzed by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), which is a water soluble enzyme commonly used in peptide synthesis. The density of cell adhesion ligands, a critical regulator of cellular phenotype following adhesion to a biomaterial. (Massia and Hubbell, J. Cell Biol. 114:1089-1100, 1991; Mooney et al., J. Cell Phys. 151:497-505, 1992; and Hansen et al., Mol. Biol. Cell 5:967-975, 1994) can be readily varied over a 5-order of magnitude density range.

Device Construction

The scaffold structure is constructed out of a number of different rigid, semi-rigid, flexible, gel, self-assembling, liquid crystalline, or fluid compositions such as peptide polymers, polysaccharides, synthetic polymers, hydrogel materials, ceramics (e.g., calcium phosphate or hydroxyapatite), proteins, glycoproteins, proteoglycans, metals and metal alloys. The compositions are assembled into cell scaffold structures using methods known in the art, e.g., injection molding, lyophilization of preformed structures, printing, self-assembly, phase inversion, solvent casting, melt processing, gas foaming, fiber forming/processing, particulate leaching or a combination thereof. The assembled devices are then implanted or administered to the body of a subject.

The device is assembled in vivo in several ways. The scaffold is made from a gelling material, which is introduced into the body in its ungelled form where it gels in situ. Exemplary methods of delivering device components to a site at which assembly occurs include injection through a needle or other extrusion tool, spraying, painting, or methods of deposit at a tissue site, e.g., delivery using an application device inserted through a cannula. In one example, the ungelled or unformed scaffold material is mixed with bioactive substances and/or cells prior to introduction into the body or while it is introduced. The resultant in vivo/in situ assembled scaffold contains a mixture of these substances and/or cells.

In situ assembly of the scaffold occurs as a result of spontaneous association of polymers or from synergistically or chemically catalyzed polymerization. Synergistic or chemical catalysis is initiated by a number of endogenous factors or conditions at or near the assembly site, e.g., body temperature, ions or pH in the body, or by exogenous factors or conditions supplied by the operator to the assembly site, e.g., photons, heat, electrical, sound, or other radiation directed at the ungelled material after it has been introduced. The energy is directed at the scaffold material by a radiation beam or through a heat or light conductor, such as a wire or fiber optic cable or an ultrasonic transducer. Alternatively, a shear-thinning material, such as an ampliphile, is used which re-cross links after the shear force exerted upon it, for example by its passage through a needle, has been relieved.

Suitable hydrogels for both in vivo and ex vivo assembly of scaffold devices are well known in the art and described, e.g., in Lee et al., 2001, Chem. Rev. 7:1869-1879. The peptide amphiphile approach to self-assembly assembly is described, e.g., in Hartgerink et al., 2002, Proc. Natl. Acad. Sci. U.S.A. 99:5133-5138. A method for reversible gellation following shear thinning is exemplified in Lee et al., 2003, Adv. Mat. 15:1828-1832

A multiple compartment device is assembled in vivo by applying sequential layers of similarly or differentially doped gel or other scaffold material to the target site. For example, the device is formed by sequentially injecting the next, inner layer into the center of the previously injected material using a needle, forming concentric spheroids. Non-concentric compartments are formed by injecting material into different locations in a previously injected layer. A multi-headed injection device extrudes compartments in parallel and simultaneously. The layers are made of similar or different scaffolding compositions differentially doped with bioactive substances and different cell types. Alternatively, compartments self-organize based on their hydro-philic/phobic characteristics or on secondary interactions within each compartment.

Compartmentalized Device

In certain situations, a device containing compartments with distinct chemical and/or physical properties is useful. Such a configuration is particularly useful when separating quarantined cell populations undergoing elimination from the outside tissue. For instance, the process or byproduct of cell destruction could interfere with the ability of non-target cells to pass through the device and remain unaffected. Therefore, it is advantageous to have multiple compartments, some of which serve to contain harmful agents or cells from gaining access to healthy tissue. Alternatively, the device captures multiple undesirable cell types and sorts them into different chambers of the device where these cell populations contact bioactive compositions containing unique combinations of attractive, adhesive, and destructive agents.

A compartmentalized device is designed and fabricated using different compositions or concentrations of compositions for each compartment. For example, and engineered cell population with means to induce death of target cells is encapsulated within hydrogels, using standard encapsulation techniques (e.g., alginate microbead formation). This first hydrogel contains factors required to maintain and contact these engineered cells with target cells, either by their covalent coupling to the polymer forming the gel or by their slow and sustained release from the gel. This compartment is then coated with a second layer of gel (e.g., double layered alginate microbeads) that contains factors that do not support the survival of these engineered cells, but instead adhere target cells in order to expose them to the engineered population in a controlled manner. This second compartment is formed from the same material that contains distinct factors (e.g., attractive and/or adhesive ligands), the same material in a distinct form (e.g., varying mechanical properties or porosity), or a completely different material that provides appropriate chemical/physical properties.

Alternatively, the compartments are fabricated individually, and then adhered to each other (e.g., a “sandwich” with an inner compartment surrounded on one or all sides with the second compartment). This latter construction approach is accomplished using the intrinsic adhesiveness of each layer for the other, diffusion and interpenetration of polymer chains in each layer, polymerization or cross-linking of the second layer to the first, use of an adhesive (e.g., fibrin glue), or physical entrapment of one compartment in the other. The compartments self-assemble and interface appropriately, either in vitro or in vivo, depending on the presence of appropriate precursors (e.g., temperature sensitive oligopeptides, ionic strength sensitive oligopeptides, block polymers, cross-linkers and polymer chains (or combinations thereof), and precursors containing cell adhesion molecules that allow cell-controlled assembly). Multiple compartments are designed to capture and either contain or eliminate target cells appropriately. In addition, the device is designed to have a number of compartments, in which cells enter in parallel, in contrast to serially passing through all compartments. The different compartments each capture target cells induce cell death of the contained cells by a unique mechanism, and in this manner provide a means to either remove the same target cell type by a variety of methods or to remove multiple target cell types by unique methods most appropriate for each captured population. An individual with ordinary skill in the art of medicine and biomaterials can readily derive a number of potentially useful designs for a given starting cell type and desired daughter cell output.

Alternatively, the compartmentalized device is formed using a printing technology. Successive layers of a scaffold precursor doped with bioactive substances and/or cells is placed on a substrate then cross linked, for example by self-assembling chemistries. When the cross linking is controlled by chemical-, photo- or heat-catalyzed polymerization, the thickness and pattern of each layer is controlled by a masque, allowing complex three dimensional patterns to be built up when un-cross-linked precursor material is washed away after each catalyzation. (W T Brinkman et al., Photo-cross-linking of type 1 collagen gels in the presence of smooth muscle cells: mechanical properties, cell viability, and function. Biomacromolecules, 2003 July-August; 4(4): 890-895.; W. Ryu et al., The construction of three-dimensional micro-fluidic scaffolds of biodegradable polymers by solvent vapor based bonding of micro-molded layers. Biomaterials, 2007 February; 28(6): 1174-1184; Wright, Paul K. (2001). 21st Century manufacturing. New Jersey: Prentice-Hall Inc.) Complex, multi-compartment layers are also built up using an inkjet device which “paints” different doped-scaffold precursors on different areas of the substrate. Julie Phillippi (Carnegie Mellon University) presentation at the annual meeting of the American Society for Cell Biology on Dec. 10, 2006; Print me a heart and a set of arteries, Aldhouse P., New Scientist 13 April 2006 Issue 2547 p 19.; Replacement organs, hot off the press, C. Choi, New Scientist, 25 Jan. 2003, v2379. These layers are built-up into complex, three dimensional compartments. The device is also built using any of the following methods: Jetted Photopolymer, Selective Laser Sintering, Laminated Object Manufacturing, Fused Deposition Modeling, Single Jet Inkjet, Three Dimensional Printing, or Laminated Object Manufacturing.

Incorporation of Compositions into/onto a Scaffold Device

Bioactive substances that influence attraction, adhesion, and cell death are introduced into or onto the scaffold structures. Cell-cell adhesion molecules (cadherins, integrins, ALCAM, NCAM, proteases) are optionally added to the scaffold composition.

The release profiles of bioactive substances from scaffold devices is controlled by both diffusion and polymer degradation, the dose of the compound loaded in the system, and the composition of the polymer. Similarly, the range of action (tissue distribution) and duration of action, or spatiotemporal gradients of these substances are regulated by these variables. The diffusion and degradation of the factors in the tissue of interest is optionally regulated by chemically modifying the factors, or by an activity limiting factor of the substance itself, i.e., the half-life of radioisotope limits the duration of its emission into nearby tissue.

The bioactive substances are added to the scaffold compositions using known methods including surface absorption, physical immobilization, e.g., using a phase change to entrap the substance in the scaffold material. For example, a growth factor is mixed with the scaffold composition while it is in an aqueous or liquid phase, and after a change in environmental conditions (e.g., pH, temperature, ion concentration), the liquid gels or solidifies thereby entrapping the bioactive substance. Alternatively, covalent coupling, e.g., using alkylating or acylating agents, is used to provide a stable, long-term presentation of a bioactive substance on the scaffold in a defined conformation. Exemplary reagents for covalent coupling of such substances are provided in the table below.

Methods to covalently couple peptides/proteins to polymers Functional Group of Reacting groups on Polymer Coupling reagents and cross-linker proteins/peptides —OH Cyanogen bromide (CNBr) —NH₂ Cyanuric chloride 4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methyl- morpholinium chloride (DMT-MM) —NH₂ Diisocyanate compounds —NH₂ Diisothoncyanate compounds .—OH Glutaraldehyde Succinic anhydride —NH₂ Nitrous Acid —NH₂ Hydrazine + nitrous acid —SH —Ph—OH —NH₂ Carbodiimide compounds (e.g., EDC, DCC)[a] —COOH DMT-MM —COOH Thionyl chloride —NH₂ N-hydroxysuccinimide N-hydroxysulfosuccinimide + EDC —SH Disulfide compound —SH [a]EDC: 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride; DCC: dicyclohexylcarbodiimide

Bioactive substances are capable of attracting target cell types toward or into the device and adhering target cell types upon contact. Other preferred bioactive substances are capable inducing cell death of captured cells, or target cell types in close proximity of the device. Such bioactive substances are used alone or in combination to achieve the desired result.

EXAMPLES Example 1 Collection and Removal of Microorganisms to Prevent, Diagnose, or Treat Infectious Disease

Hosts exposed to or infected by invasive microorganisms such as viruses, bacteria, protozoa, fungi, or worms, typically do not present symptoms of infection immediately. By the time the host presents outward signs of an infection, ingested microorganisms have likely matured, multiplied, spread, or inflicted damage upon host tissues. The subject is identified as planning to be located in an environment characterized by the presence of such a pathogen or having recently been located in such an environment. The scaffold composition is administered to the host subject either prior to or following exposure to these microorganisms, wherein the device captures microorganism by filtration or specific adhesion proteins contained within a bioactive composition. When the device is administered very soon after exposure, the device eliminates microorganisms, and prevents the spread of infection. Alternatively, the device is administered and collected in order to identify the infectious agent to which the subject was exposed prior to the emergence of symptoms, providing a valuable head-start on diagnosing and treating future disease. Moreover, the scaffold is administered to non-human species residing in areas of suspected infestation in order to identify potential threats to humans living in nearby as a preventative measure.

The impact of this diagnostic innovation for microorganisms can only be fully appreciated in light of the number of microorganisms that can cause disease. Exemplary viral classes that infect human hosts include, but are not limited to: adenoviruses, herpesviruses, poxviruses, parvoviruses, papovaviruses, hepadnaviruses, orthomyxoviruses, paramyxoviruses, coronaviruses, picornaviruses, reoviruses, togaviruses, flaviviruses, arenaviruses, rhabdoviruses, and retroviruses. The common names for some of the diseases caused by the viral classes listed above include: smallpox, fifth disease, HPV, HBV, kidney disease, influenza, mumps, measles, subacute sclerosing panenephalitis, RSV, cold, poliomyelitis, hand-foot-and -mouth disease, nonspecific febrile illness, croup, bronchitis, pneumonia, hepatitis, pancreatitis, arthritis, diabetes, meningitis, encephalitis, paralysis, viral myocarditis, HAV, gastroenteritis, diarrhea, respiratory distress, rubella, respiratory tract, yellow and dengue Fever, aseptic meningitis, acute viral haemorrhagic illness, rabies, leukemia, HTLV-I-associated myelopathy, and AIDS.

Exemplary bacterial strains that infect human hosts include, but are not limited to: Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Neisseria gonorrhoeae, Neisseria meningitides, Corynebacteria diphtheriae, Bacillus anthracis, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Salmonella typhae, Shigella, Campylobacter, Vibrio chloerae, Yersinia pestis, Pasteurella, Pseudomonas aeruginosa, Brucella Haemophilus, influenzae, Legionella, Bordetella, Clostridium tetani, Clostridium botulinum, Clostridium perfringens, Treponema pallidum, Borrelia burgdorferi, Leptospira interrogans, Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium avium, Rickettsia prowazekii, Chlamydia trachomatis, and Mycoplasma pneumoniae. The common names for some of the diseases or conditions caused by the bacteria listed above are: toxic shock syndrome, pneumonia, acute sinusitis, otitis media, meningitis, osteomyelitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis, brain abscess, tonsilitis, scarlet fever, glomerulonephritis, rheumatic fever, gonorrhoea, meningitis, diphtheria, anthrax, listeriosis, sepsis, gastroenteritis, typhoid fever, diarrhea, anorexia, salmonellosis, bacillary dysentery, Guillain-Barré syndrome, cholera, bubonic plague, cellulitis, wound infection, brucellosis, meningitis, bacteremia, cellulitis, osteomyelitis, epiglottitis, joint infection, sinusitis, Legionnaires' disease, pertussis or whooping cough, tetanus, botulism, tissue necrosis, bacteremia, emphysematous cholecystitis, gas gangrene, syphilis, kidney damage, Lyme arthritis, Lyme disease, tuberculosis, leprosy, typhus, rheumatoid arthritis, prostatitis, epididymitis, cervicitis, urethritis, and infertility.

Protozoa that infect human host include, but are not limited to: Entamoeba histolytica, Giardia, Leishmania, Plasmodium (falciparum, vivax), Trypanosoma (brucei), Toxoplasma gondii, and Cryptosporidium. Diseases/conditions caused by the protozoa listed above include, but are not limited to: Giardiasis, cutaneous (localized and diffuse) infections, visceral infections, fever, swelling of the liver and spleen, anemia, Malaria, sleeping sickness, Toxoplasmosis, and Cryptosporidiosis.

Fungi that infect human hosts include, but are not limited to: Candida albicans, Cryptococcus neoformans, Aspergillus, Histoplasma capsulatum, Coccidioides immitis, and Pneumocystis carinii. Diseases or conditions caused by the fungi listed above are: Candidiasis; skin, lung, and meningeal infections; fever, cough, chest pain or breathlessness; Histoplasmosis; Coccidioidomycosis (Valley Fever), and Pneumonia.

Worms that infect human hosts include, but are not limited to: Trichuris trichiura, Trichinella spiralis, Enterobius vermicularis, Ascaris lumbricoides, Ancylostoma, Strongyloides, Filaria, Onchocerca volvulus, Loa loa, Dracuncula medinensis, Schistosoma (mansoni), and Clonorchis sinensis. Diseases or conditions caused by worms listed above include, but are not limited to: human whipworm, roundworm, trichuriasis, Trichinosis, Pinworm, Ascariasis, Hookworm; intellectual, cognitive and growth retardation; intrauterine growth retardation, prematurity, and low birth weight; elephantiasis, Lymphatic Filariasis; river blindness; Calabar swellings; Dracunculiasis/Guinea worm disease (GWD); Schistosomiasis; liver and intestinal damage.

For example, the scaffold composition is packaged into a gelatin-coated pill and administered orally, releasing a multiple number of scaffold compositions within the gastrointestinal tract of the host subject. For diagnosis, collection of the scaffolds occur using a stool sample from the subject. This method of internalizing and collecting the device avoids exposure of the host and administrator to blood, which is particularly useful in regions of the world where blood-born viral infections, like AIDS, are prevalent. The device is alternatively introduced by intravenous, intraperitoneal, or intramuscular injections, as well as lumbar puncture, subcutaneous implantation, or surgical methods depending on the target site of interest.

Example 2 Capture and Collection of Circulating Mammalian Cells to Diagnose Disease

The device is also used to diagnose disease caused by mammalian or eukaryotic cells, whereby it is administered into a host and collected. Following collection, the device is manipulated to yield its contents in order to allow for the identification of undesirable mammalian cells that circulate within the host, such as cancer cells undergoing metastasis from their primary tumor location, leukemia, lymphoma, sickle-shaped blood cells, or immune cells contributing to inflammation. Often a subject can be afflicted with primary cancer tumors affecting multiple organs all of which could metastasize and travel through the blood stream, lymphatic fluid, or cerebral spinal fluid (CSF). To quickly diagnose which tumor is contributing to the metastasis, and to avoid the unnecessary risk of surgery or multiple biopsies, the device is used to collect these cells for identification based either on molecular expression profiles or cell morphological features.

Example 3 Elimination of Neoplasms by Implantation of a Biodegradable Device

To counteract the growth of either malignant or benign neoplasms, which could become malignant, the device is implanted either by subcutaneous or intraperitoneal injection, or by surgical implantation, at the site of abnormally rapid cell replication. Once in place, the scaffold composition adheres to adjacent tissue and a bioactive composition that is either tethered to the scaffold or allowed to disseminate from the scaffold at close range, induces death of the rapidly dividing cell population. In this case, the scaffold degrades over time and does not require collection. A significant advantage of using the scaffold composition to reduce neoplastic growth, is that devices located around the tumor borders capture cells that attempt to escape from the tumor, thus, preventing them from spreading outside of their local niche.

Example 4 To Remove Blockages from Arterial Walls Using the Device as a Stent

To combat high blood pressure and minimize the risk of stroke, the device is introduced into the circulatory system by one of two methods: the scaffold is either used as an arterial stent in order to either remain stationary and allow the blood to pass through, or as a mobile device that flows along with blood in order to gain access to the entire body. As an arterial stent, the device reduces or eliminates the accumulation of compounds and/or cells that threaten to block the normal flow of blood. As a mobile device, the scaffold composition prevents the future occlusion of arteries by eliminating these compounds and/or cells before they can attach to the arterial walls.

Example 5 Device Implantation for the Permanent Removal of Adipocytes to Accomplish Life-Long Weight Loss

Another use for the scaffold composition is “surgery-less liposuction.” Many subjects are incapable of overcoming morbid obesity due to what is now considered a chemical addition to food. Methods to alter lifestyle and surgical intervention to limit the capacity of the body to intake calories have met with limited success. However, the elimination of adipocytes, or fat cells, from the body by means of destroying them locally, is more permanent solution the success of which does not depend upon the subject to maintain a proper diet. This therapeutic strategy relieves the chemical and physical threats that inflated adipocytes pose on the internal organs of morbidly obese subjects. To reduce or eliminate adipocytes, the scaffold composition is delivered by subcutaneous or intraperitoneal injection, or surgical implantation, into target sites where it captures or adheres to, and subsequently destroys adipocytes until the scaffold itself degrades.

Example 6 Prevention of Glial Scars that Physically Prohibit Central Nerve Regeneration

A unique property of the central nervous system, as opposed to the peripheral nervous system, is the inhibition of nerve regeneration. While researchers have identified the signaling molecules that prevent central nerve re-growth, Nogo ligands and their receptors, another factor that threatens the success of regenerative treatments is glial scarring. Glial cells, which normally support neuronal function, respond to nerve injury by increasing replication and invading the site of damage, thus forming a physical blockade against nerve outgrowth. The scaffold composition is delivered to the site of central nerve injury, and a bioactive composition is incorporated having means to specifically adhere, capture, and destroy glial cells that accumulate close to the site of nerve injury. Thus, the device prevents a glial scar from impeding regeneration. Furthermore, inhibitors of Nogo or blocking agents of the Nogo receptor diffuse from a bioactive composition further incorporated into the scaffold composition to eliminate molecular signals that would also inhibit regeneration.

Example 7 In Vivo Clearance of Amyloid Protein Plaques Associated with Alzheimer's Disease

Current research into the field of neurodegenerative disease has provided important insights into the mechanisms behind some of our most debilitating diseases. For example, Alzheimer's Disease (AD) is tentatively diagnosed in living subjects based primarily on behavioral affects and, in some cases, genetic tests which can show predisposition only. The final diagnosis for AD is made postmortem, and the presence of protein plaques on the brain provides the final confirmation. To diagnose, retard, or arrest the formation of amyloid plaques in the brains of suspected AD patients, the device is injected into the cerebral spinal fluid by lumbar puncture wherein the scaffold composition contains immune cells capable of clearing cellular debris, and wherein the scaffold composition adheres to amyloid protein, thus allowing these resident cells to clear AD-related depositions. The devise is constructed of a non-biodegradable material and remains in the central nervous system to eliminate future deposits from accumulating.

Example 8 Prevention or Inhibition of Autoimmune Disease

Autoimmune disorders, e.g. those of the central nervous system are characterized by neurodegeneration and inappropriate immune system responses. For instance, multiple sclerosis is an autoimmune condition in which the host's immune system incorrectly recognizes nerve fibers as foreign cells, leading to their demyelination and, ultimately, to death of the host. To retard or arrest the progression of MS, the device is injected into the cerebral spinal fluid via lumbar puncture, or contacted to either brain or spinal cord tissue by surgical methods, wherein a bioactive composition incorporated into the scaffold composition, containing self-antigens (pre-isolated from the given subject) and chemokines, attracts, captures, and eliminates immune cells that contribute to immune system attacks of host tissues.

Other Embodiments

While the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.

The patent and scientific literature referred to herein establishes the knowledge that is available to those with skill in the art. All United States patents and published or unpublished United States patent applications cited herein are incorporated by reference. All published foreign patents and patent applications cited herein are hereby incorporated by reference. All other published references, documents, manuscripts and scientific literature cited herein are hereby incorporated by reference.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. 

1. A device comprising a scaffold composition and bioactive composition, said bioactive composition being incorporated into or conjugated onto said scaffold composition, wherein said scaffold composition or said bioactive composition captures an undesirable cell, or wherein said scaffold composition or said bioactive composition destroys an undesirable cell. 2.-5. (canceled)
 6. A method of making a scaffold, comprising providing a scaffold composition, covalently linking said scaffold composition with a first bioactive composition comprising proteins with means for binding an undesirable cell, and contacting said scaffold composition with a second bioactive composition, wherein said second bioactive composition is covalently or non-covalently associated with said scaffold composition wherein said second bioactive composition comprises a cytotoxic or cytostatic agent.
 7. The method of claim 6, wherein said linking and contacting steps are repeated to yield a plurality of layers, wherein said second bioactive composition comprises a combination of compounds with means to eliminate an undesirable cell.
 8. A method of removing or eliminating a microorganism or target cell from a mammal, comprising administering to a subject exposed to or infected by said microorganism or target cell, a device comprising a scaffold composition and bioactive composition, said bioactive composition being incorporated into or conjugated onto said scaffold composition, wherein said scaffold composition or bioactive composition captures said microorganism or target cell, thereby sequestering said microorganism or target cell from the host environment.
 9. The method of claim 8, further comprising the step of exposing said microorganism or target cell to said bioactive composition, wherein said scaffold composition or said bioactive composition induces death of said microorganism or target cell.
 10. (canceled)
 11. The method of claim 8, wherein said scaffold composition disseminates said bioactive composition.
 12. The device of claim 1, wherein said scaffold composition has one or more of the following characteristics: (a) comprises a non-biodegradable material; (b) comprises a non-biodegradable material selected from the group consisting of a metal, a plastic polymer, or a silk polymer; (c) comprises a biocompatible material; (d) is non-toxic; (e) is non-immunogenic; (f) contains a solid external surface; (g) contains a porous external surface; (h) contains a solid internal surface; (i) contains a porous internal surface; or (j) comprises one or more compartments. 13.-15. (canceled)
 16. The device of claim 1, wherein said bioactive composition is covalently or non-covalently linked to the scaffold composition.
 17. The device of claim 1, wherein said bioactive composition comprises an element either covalently or non-covalently bonded to the surface of the scaffold composition, with means to bind a target cell.
 18. The device of claim 17, wherein said element is a secreted or membrane-bound amino acid, peptide, protein, polymer, or chemical.
 19. The method of claim 7, wherein said undesirable cell comprises a host cell, a foreign cell, a stem cell, a differentiated cell, a dividing cell, a migrating cell or a circulating cell.
 20. The device of claim 19, wherein said host cell displays host surface antigens or wherein said foreign cell displays non-host surface antigens. 21.-24. (canceled)
 25. The device of claim 12, wherein said external surface, said internal surface or both said external surface and internal surface are porous, wherein said pore size is less than about 10 nm, in the range of about 100 nm-20 μm in diameter, or greater than about 20 μm.
 26. The method of claim 8, wherein said microorganism is a virus, bacteria, fungus, protozoan, worm, a spore, an immature cell, or a vegetative cell.
 27. The method of claim 26, wherein said microorganism is: (a) a virus selected from the group consisting of adenoviruses, herpesviruses, poxviruses, parvoviruses, papovaviruses, hepadnaviruses, orthomyxoviruses, paramyxoviruses, coronaviruses, picornaviruses, reoviruses, togaviruses, flaviviruses, arenaviruses, rhabdoviruses, and retroviruses, (b) a bacteria selected from the group consisting of Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Neisseria gonorrhoeae, Neisseria meningitides, Corynebacteria diphtheriae, Bacillus anthracis, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Salmonella typhae, ShiellaCalobacter Yersinia Pseudomonas aeruginosa, Brucella Haemophilus, influenzae, Legionella, Bordetella, Clostridium tetani, Clostridium botulinum, Clostridium perfringens, Treponema pallidum, Borrelia burgdorferi, Leptospira interrogans, Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium avium, Rickettsia prowazekii, Chlamydia trachomatis, and Mycoplasma pneumoniae; (c) a fungus selected from the group consisting of Candida albicans, Cryptococcus neoformans, Aspergillus, Histoplasma capsulatum, Coccidioides immitis and Pneumocystis carinii; (d) a protozoan selected from the group consisting of Entamoeba histolytica, Giardia, Leishmania, Plasmodium (falciparum, vivax), Trypanosoma (brucei), Mxoplasma gondii, and Cryptosporidium; or (e) a worm selected from the group consisting of Trichuris trichiura, Trichinella spiralis, Enterobius vermicularis, Ascaris lumbricoides, Ancylostoma, Stron loides Filaria Onchocerca volvulus Loa loa, Dracuncula medinensis, Schistosoma (mansoni), and Clonorchis sinensis. 28.-32. (canceled)
 33. The method of claim 6, wherein said second bioactive composition is a protein, an organic compound, an inorganic compound, a radioisotope, an antibiotic compound, an antiviral compound, an antiparasitic compound, an engineered virus, an activated immune cell, a toxin, a natural compound or a synthetic compound. 34.-45. (canceled)
 46. The method of claim 8, wherein said device is administered orally, systemically, by lumbar puncture to access cerebral spinal fluid, subcutaneously, transcutaneously, as an arterial stent, or surgically. 47.-51. (canceled)
 52. The method of claim 8, further comprising the step of collecting said device from the mammal, thereby allowing the composition of captured cells to be analyzed or identified.
 53. The device of claim 1, wherein said bioactive composition comprises a multivalent acrylamide polymer, polylysine tagged with a sugar or an amino acid, a cytokine, a chemokine, an adhesin, a polysaccharide, a sugar sialic acid, a capsid-binding protein, a viral attachment protein, an isolated plasma membrane fraction from a cellular target, an integrin, an Ig superfamily member, a cadherin, a selectin, a phagocytic cell, an engineered virus, an antibody, a pro-apoptotic ligand, a caspase-activator, a radioactive isotope, a toxin, or a chemotherapy agent.
 54. The device of claim 1, wherein said bioactive composition comprises fibronectin, laminin, collagen, thrombospondin 1, vitronectin, elastin, tenascin, aggrecan, agrin, bone sialoprotein, cartilage matrix protein, fibrinogen, fibrin, fibulin, a mucin, entactin, osteopontin, plasminogen, restrictin, serglycin, SPARC/osteonectin, versican, von Willebrand Factor, polysaccharide heparin sulfate, a connexin, collagen, a RGD (Arg-Gly-Asp) peptide or cyclic peptide, a YIGSR (Tyr-Ile-Gly-Ser-Arg) peptide or cyclic peptide, a glycosaminoglycan (GAG), hyaluronic acid (HA), condroitin-6-sulfate, an integrin ligand, a neural cell adhesion molecule (NCAM), an intercellular adhesion molecule (ICAM), a vascular cell adhesion molecule (VCAM-1), a platelet-endothelial cell adhesion molecule (PECAM-1), L1 or CHL1. 